Piston



April 18, 1933. 1,904,305v

P. M. FREER PISTON Filed March 50, 1931 lNvENToh yn 2% M 53;

ATTORNEYIS zone of the wrist pin receiving means.

Patented Apr. 18, 1933 c UNITED STATES PHELPS M. FREER, OFIDEETROIT, MICHIGAN PISTON Application filed March 30,1931. Serial N0. 526,481.

The invention relates to pistons and refers more particularly to pistons formed of a metal, such as aluminum or an aluminum alloy, and adapted for use in internal combus- 1 .5 tion engines. The invention has for one of its objects to so construct the piston that its outer member which carries the boss means for receiving a wrist pin and may be readlly cast and permits of thense of a single or a 10 one-piece metal core. Another object is to construct the outer member with means for receiving a piston ring, as well as means for receiving a wrist pin, and with an outwardly and upwardly tapered inner face from th: further object is to close the upper end of this outer member in an effective manner. These and other objects of the invention will become apparent from the following description, taken in connection with the accompanying drawing, in which I Figures 1 and 2 are axial sections at right angles to each other through a piston showing an embodiment of my lnventlon;

Figures 3 and 4: are similar views showing another embodiment of my inventlon;

Figures 5 and 6 are detail views showing another method of securing the inner memher to the outer member.

As shown in Figures 1 and 2, the piston comprises the head 1 and the skirt 2. The head is preferably formed of aluminum or an aluminum alloy and the skirt is preferably formed of iron. The skirt may be secured to the head by sitable means, such as the radially extending coil springs 3.

The head comprises the hollow outer member 4 which is provided with the annular grooves 5 for' receiving the piston rings and 0 with the integral inwardly extending bosses 6 having their axes in alignment transversely of the outer member. The inner face of the outer member upwardly beyond the zone and more particularly the plane extending through the axes of the bosses and transv gages the annular shoulder 8.

former and additionally by the radially ex- -with the integral inwardly extendingbosses 14: having aligned axes extending transversely of the skirt and adapted to receive the wrist pin. The-portion of the inner face of versely of the outer member is slightlytapered upwardly'and outwardly to provide the necessary draft or clearance permitting of the use of a single or a one-piece metal core when casting the outer member. The outer vmember has at its upper end the enlarged recess 7 which provides the transversely extendlng internal annular shoulder 8 spaced downwardly from the upper edge of the outer member. Y

j The head also comprises the inner member 9whioh is in the nature of aplate and has its rim portion 10 only engagingthe outer member. The periphery of this rim portion engages the periphery of the enlarged recess 7 and the lower face of the rim portion en- The inner member 9 is rigidly secured in the outer member 1 by shrinking the latter upon the tending pins 11 which extend through the wall of the outer member, and into the inner member. It will be seen that this inner member forms the major portion of the upper end of the head and that most of the ex plosive load upon the inner member is carried into the outer member through the internal annular shoulder upon the latter.

In the modification shown in Figures 3 and 4:, the piston has the skirt 12 which, as shown, is formed of aluminum or an aluminum alloy. This skirt is provided with the annular grooves 13 for receiving thepiston rings and the skirt upwardly beyond the zone and more particularly the plane passing through the axes of the bosses and extending transversely of the skirt is slightly tapered upwardly and outwardly to provide the draft or clearance permitting of the use of a single or a onepiece metal core when-casting this skirt. The piston also has the inner member 15. which portion and bosses for the wrist pin,

is preferably formed of aluminum or an aluminum alloy and is the same as the inner member 9 and is secured to the skirt 12 in the same manner as the inner member 9 is secured to the outer member 1.

As shown in Figures and 6, the inner member 16 is secured to the outer member 17 by shrinking the outer member upon the inner member and by turning over or peening the annular projection 18 at the upper inner edge of the outer member against the inner member. The inner member is secured in place against the internal annular shoulder 19 of the outer member and the inner member has its upper edge bevelled at 20 to receive the projection 18 so that the upper faces of the inner and outer member when secured together are flush.

What I claim as my invention is: v

1. A piston comprising an annular member having its upper face in and exposed to the combustion chamber, said member including an integral ring groove portion and bosses for the wrist pin and being also fashthrough its upper end of a corresponding single piece core and an inner member secured within said annular member and completing the head.

2. A piston comprising an annular member having its upper face in and exposed to the combustion chamber and forming a substantial portion of the area of the head, said member including an integral'ring groiye 8- ing also fashioned to provide draft for withdrawal through its upper end of a corresponding single piece core and having an enlarged recess at its upper end providing an annular shoulder, and an inner member secured within said recess and forming a com- :plementary portion of the head.

3. A piston comprising an annular member having its upper face in and exposed to the combustion chamber and forming a substantial portion of the area of the head, said member including an integral ring groove portion and bosses for the wrist pin, being also'fashioned to provide draft for withdrawal through its upper end of a corresponding single piece core and having an enlarged recess at its upper end providing a shoulder, and an insert having a shrunk fit Within said recess forming a complementary portion of the head, the area of the periphery of said insert in contact with the wall of the'recess equalling a substantial portion of the area exposed to the combustion chamber whereby good thermal conductivity between said insert and annular member is obtained.

4. A piston comprising an annular member having its upper face exposed to the combusion chamber, said member including an integral ring groove portion and bosses for the wrist pin being also fashioned to pro- PHELPS M. FREER.

ioned to provide draft for withdrawal 

